Dimethoxymethane (I) was oxidized with N-diluted O (O concn. 9%) to CH(2)O in presence of MeOH (3.98%) and H(2)O (2.53%) over an Fe-Mo catalyst at 240-320 degrees C (O/I mole ratio 1.5-3.0, calatyst load 5-30 m(3/)Lh, flow intensity 50-150 L/h to det. the optimum conditions of the reaction. No substantial effect of the 08 ratio on /conversion was obsd. The / conversion showed a max. at flow intensity 100 L/h. Under optimum conditions, the / conversion reached about 99%. The process selectivity was about 90%.